I have an older Intel laptop that has a 1600x900 display, and I find that if I put the machine to sleep, connect an external monitor with a higher resolution, and then turn it back on, the login screen doesn't adjust to the new resolution and it reveals what I had open (see photo).
However, I'm not that familiar with Linux Mint (even though I've daily driven Linux for nearly 10 years, I very casually use LMDE) and I'm not sure if this is a Cinnamon problem or if the lock screen is under a different program.
Looking at Linux Mint's webpage on reporting a bug (https://projects.linuxmint.com/reporting-an-issue.html) they seem to mostly use Cinnamon as an example, but I don't want to report this issue as a Cinnamon issue if it's the wrong project.
In case this is platform specific, my device's details are below:
- Host: Dell Latitude E6420
- CPU: Intel Core i7-2630QM (Sandy Bridge)
- GPU: Intel 2nd Generation Core Processor Family
- Kernel: 6.1.0-21-amd64
- DE: Cinnamon 6.0.4
- WM: Mutter (Muffin)
- Display Server: X11
I've never filed a bug report in my life before, usually I just put up with the issue until it's eventually fixed, but I feel this is a moderate security issue that should be flagged.
Go ahead and report it to the Mint team. Even if it is an issue upstream, they will verify the issue and then report it as well. Never hesitate to report a bug you find, especially if it's a security or privacy issue.
Even if the bug is a duplicate, it helps to know other people are having the same issue. At worst they will mark your report as a duplicate, which will let you know they are aware of the issue.
Keep in mind that if it is a serious security issue many projects have a way of reporting them separately from other bug reports so the issues can be patched before being published.